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  #1  
Old 09-11-2016, 05:20 PM
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Location: Ecuador, Quito
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190E fuel/oxygen mixture without lambda on/off ratio

Hi all!.
I own a 1986 190E, manual transmission, engine 102 962 101.
I've been having a problem long time ago. My benz does not have lambda oxygen sensor nor pin 3 in the x11 diagnotic socket thus i can't measure the lambda ration with duty cycle and now it is consuming a lot of fuel and hesitate when I accelerate .

I wonder if there is any way to calibrate the mixture, similar as the 50% with duty cycle?

Thank you all! and sorry for my english

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  #2  
Old 09-11-2016, 05:58 PM
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Quote:
Originally Posted by joan1094 View Post
Hi all!.
I own a 1986 190E, manual transmission, engine 102 962 101.
I've been having a problem long time ago. My benz does not have lambda oxygen sensor nor pin 3 in the x11 diagnotic socket thus i can't measure the lambda ration with duty cycle and now it is consuming a lot of fuel and hesitate when I accelerate .

I wonder if there is any way to calibrate the mixture, similar as the 50% with duty cycle?

Thank you all! and sorry for my english
Ummm

CIS and no oxygen sensor on a W201?

I didn't think "they" did that


OK


If you can't measure "burning" by measuring the oxygen sensor's output then you need to adjust by measuring the emissions - get an exhaust gas analyser.

Alternatively if that is too expensive there's a product called colour tune made by Gunson that might give you a better idea of how the engine is burning fuel at idle speeds and slightly above. (Not a product I've had much success with in the past though - exhaust analyser is way way better)
__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!
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  #3  
Old 09-11-2016, 06:01 PM
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Join Date: Feb 2011
Location: Modesto CA
Posts: 2,966
Quote:
Originally Posted by joan1094 View Post
Hi all!.
I own a 1986 190E, manual transmission, engine 102 962 101.
I've been having a problem long time ago. My benz does not have lambda oxygen sensor nor pin 3 in the x11 diagnotic socket thus i can't measure the lambda ration with duty cycle and now it is consuming a lot of fuel and hesitate when I accelerate .

I wonder if there is any way to calibrate the mixture, similar as the 50% with duty cycle?

Thank you all! and sorry for my english
1) Do you know if the oxygen sensor is missing, or was removed, or was the car produced without that sensor for Ecuador? [The absence of a pin in the #3 position suggests that it was produced without O2 sensing.]

2) Can you post pictures of the fuel distributor and air flow meter?

Yes, the mixture can be adjusted, just not as easily as with O2 sensing.
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  #4  
Old 09-11-2016, 06:36 PM
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Location: Ecuador, Quito
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The gas analyser is a good idea, thanks, but i would like to know if can be done more precisely.
I am pretty sure the car was produced without the sensor, i've checked others W201 and w124 and mostly dont have pin 3.

Frank, what is the other way to calibrate it?

Thanks!
Attached Thumbnails
190E fuel/oxygen mixture without lambda on/off ratio-distribuidor.jpeg   190E fuel/oxygen mixture without lambda on/off ratio-x11.jpeg  
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  #5  
Old 09-11-2016, 07:47 PM
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Location: Modesto CA
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Quote:
Originally Posted by joan1094 View Post
The gas analyser is a good idea, thanks, but i would like to know if can be done more precisely.
I am pretty sure the car was produced without the sensor, i've checked others W201 and w124 and mostly dont have pin 3.

Frank, what is the other way to calibrate it?

Thanks!
The pic of the FD/airmeter is quite interesting; the package is for KE-Jetronic (aka, CIS-E). On the side of the FD is an EHA (the black plastic rectangle), which is the device that varies the mixture in response to changes in the oxygen content of the exhaust stream. The EHA receives a signal from the engine control unit (ECU), and the primary input to the ECU is the signal from the O2 sensor.
When an O2 sensor is present, and the engine is started from cold, the KE-jet system operates with a fixed current to the EHA (Open-loop mode) until the O2 sensor comes up to operating temperature and is sending a reliable signal.
If there really is no O2 sensor installed, then the system has been configured to operate permanently in Open-loop.
With all respect, after seeing the pic of the FD, there is a question in my mind about past work on the system: the injection pipes have been treated quite roughly; the bends are not as they were from the factory.
If you can access the ECU, look for a connection at pin #23; that is the source of the signal that would be seen at pin3/x11.
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  #6  
Old 09-11-2016, 08:14 PM
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Location: Ecuador, Quito
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Yea, my dad used to fix it by himself haha. I am trying to repair all that kind of mechanics. I saw the ECU and it has the pin 23 for receiving the signal, but the big socket does not, i mean, there is no metal contact, just plastic.

Open loop means that the EHA thinks that the car is at max acceleration?

I would upload pics but there is no sunlight, tomorrow i will post them
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  #7  
Old 09-12-2016, 12:39 AM
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Join Date: Feb 2011
Location: Modesto CA
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Quote:
Originally Posted by joan1094 View Post
Yea, my dad used to fix it by himself haha. I am trying to repair all that kind of mechanics. I saw the ECU and it has the pin 23 for receiving the signal, but the big socket does not, i mean, there is no metal contact, just plastic.

Open loop means that the EHA thinks that the car is at max acceleration?

I would upload pics but there is no sunlight, tomorrow i will post them
Open loop means simply that the injection system is operating without any feedback of information about the mixture. Open loop operation occurs at all throttle positions and engine speeds. In open loop mode the mixture is determined by airflow deflecting the sensor plate and thus the fuel metering plunger in the FD. If the ECU and the EHA are operational, there could be some correction of mixture for temperature, barometric pressure, and also for rate of acceleration.

If you are able, examine the exhaust manifold and the exhaust pipe connected to the manifold for a place that an O2 sensor would be screwed into the manifold or pipe. The threads would be about 19mm. Although it is not impossible, it is difficult to understand that the car would have been constructed without feedback control.
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  #8  
Old 09-12-2016, 12:52 AM
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The hole for the oxygen sensor on the early W201s was fitted to the exhaust pipe - first bit past the exhaust manifold.

#####

In this picture



I can see that the fuel pressure regulator on the front of the mixture control unit does not have the vacuum hose fitted between it and the pipe work from the engine breathing pipework. This will not only mess with the fuel but the air going into the mixture unit.

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!
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